An ionic compound and an electrolytic material containing the ionic compound are used for an ionic conductor for various cells based on ion conductivity, and utilized for electrochemical devices such as an electric field capacitor, an electric double layer capacitor, a lithium ion capacitor, a solar cell, and an electrochromic display device, in addition to cells having charge/discharge mechanism such as a primary cell, a lithium ion secondary cell, and a fuel cell.
Various compounds as an ionic compound to be used preferably for these electrochemical devices have been investigated and for example, alkali metal salts or organic cation salts of hexafluorophosphate, tetrafluoroborate, trifluoromethylsulfonylimide (TFSI), dicyanamide (DCA), tricyanomethide (TCM), and the like have been proposed.
In Patent Documents 1 and 2, among the above-mentioned ionic compounds, compounds containing anions having a structure formed by bonding a cyano group to N, C, B, or the like as a central element are investigated, and these patent documents describe that ionic compounds containing the anions having the above-mentioned structure are used preferably as electrolytes for various electrochemical devices since the ionic compounds are excellent in ion conductivity and have thermally, physically, and electrochemically stable characteristics.
Particularly, with regard to an ionic compound containing, as an anion, cyanoborate having boron as a central element, Patent Documents 3 and 4, for example, describe ionic compounds (TCB salts) containing tetracyanoborate ([B−(CN)4], hereinafter, may be referred to as TCB) as an anion. Since TCB salts shows characteristics of ionic liquids, that is, characteristics of being a liquid even at room temperature and being stable thermally, physically, and electrochemically, their production process as well as their applications for various uses are investigated (Patent Documents 3 and 4).
Further, Patent Document 5 discloses an ionic compound obtained by substituting a part of the cyano group bonded to boron of TCB with an alkoxy group or a thioalkoxy group, and describes that the ionic compound is useful as an ionic liquid or the like.